Touch control system

ABSTRACT

A touch control system that is responsive to a user input selection includes an electrically non-conducting substrate, such as glass ceramic, and at least one capacitive-responsive touch pad on the substrate. A source signal having a primary frequency that is greater than 150 kHz, and preferably in the range of between 150 kHz and 500 kHz, is applied to one portion of the touch pad. The touch pad couples the electrical signal to another portion of the touch pad in order to develop a detection signal, which is decoded in order to determine the presence of the capacitance of a user. The decoder preferably includes a peak detector composed of a low gain circuit in order to avoid distortion of the detection signal. Greatly improved performance in the presence of liquids, such as water, on the touch pad is provided. This is especially useful when the touch pad is applied to a horizontal surface, such as a cook top, upon which liquid spills may occur. A display is juxtaposed with the glass ceramic substrate and an optical correction material is provided between the display and the underlying modulated surface that imparts mechanical strength to the substrate. The optical correction material corrects optical distortion of the visual indications of the display caused by the modulated surface.

RELATED APPLICATION

This application is a continuation of application Ser. No. 08/040,188filed on Mar. 29, 1993, now U.S. Pat. No. 5,572,205.

BACKGROUND OF THE INVENTION

This invention relates generally to touch control systems and, moreparticularly, to capacitance-responsive touch control input devices forapplication to horizontal substrates, such as glass ceramic panels. Theinvention is particularly adapted for use with smooth-top induction,radiant, and halogen burner cooking appliances.

Touch control input devices that respond to the capacitance of a user'scontact in order to actuate an appliance are typically applied to avertical surface. While such orientation is primarily for theconvenience of use, it avoids several problems associated with applyingtouch controls to horizontal surfaces, such as smooth-top cookingappliances. One difficulty with application to horizontal substrates isthat there is a greater likelihood that liquids will be splashed on thetouch control applied to a horizontal surface, such as a range cook top.Such moisture tends to cause erratic operation of the input control,which could be dangerous in the case of a cooking appliance. Thisdifficulty is typically overcome by separating the touch control fromthe cooking surface in order to provide a physical barrier between thetwo. This solution is not without its drawbacks. The primary benefit ofa smooth-top cooking appliance is to eliminate the difficulty ofcleaning up from spills and boil-over getting into burner elements.While separate touch control input devices are an improvement overelectromechanical controls, which still allow places where spills canaccumulate, the requirement for a physical barrier between the cook topand the touch control is an impediment to easy cleanup and is acompromise in aesthetic appearance.

An attempt to overcome the problem caused by watery spills on thesupport surface of a smooth-top cooking appliance causing erroneousoperation of a touch control applied directly to the support surface isdisclosed in U.S. Pat. No. 4,446,350 issued to Takumi Mizukawa et al.for an INDUCTION HEATING COOKING APPARATUS. In Mizukawa et al., touchpads are provided on the upper surface of a pan supporting plate and areenclosed by guard rings of conductive material composed of a groundedconductor and an enclosing conductor. A control circuit, which isresponsive to the touch pads and the guard rings, responds to spilledwater or the like contacting the guard rings by latching a power controlcircuit at a zero power level. This resets the cooking apparatus to azero heat output condition. The solution proposed in Mizukawa et al. hasseveral difficulties. At least one of the guard rings must be connectedwith a ground potential in order to be effective. This requiresconductive leads being applied to the pan support surface, which iscostly and a potential source of failure. Additionally, Mizukawa et al.responds to spilled water by latching the cooking apparatus into a zerooutput condition. This is a nuisance to the user by requiring that thespill be wiped up and the power level of the cooking apparatus reset inorder to continue with the cooking operation.

Another difficulty with applying a touch control to a horizontalsubstrate is that code requirements, as well as conservative engineeringpractices, dictate that large horizontal panels be manufactured usingparticular materials and in a particular manner to avoid breakage due toeither mechanical impact or thermal shock. In particular, whilerelatively thin soda-lime glass may be utilized for vertical touchpanels, smooth-top cooking surfaces that are capable of supportingmultiple pans above multiple burners are made from glass ceramicmaterial having a greater thickness, on the order of three (3) to five(5) millimeters and require negligible thermal expansion. Additionally,the surface of the substrate facing away from the user is modulated, ordimpled, in order to add greater mechanical strength to the substrate.The thickness of the glass ceramic material and the modulated surfacehave prevented, in the past, application of touch control technology tosuch large horizontal substrates.

SUMMARY OF THE INVENTION

The present invention is embodied in a touch control that is responsiveto a user input selection. The control includes an electricallynon-conducting substrate and a capacitance-responsive touch pad on thesubstrate. A signal generator is provided as a source to generate anelectrical signal and to apply the signal to one portion of the touchpad. The touch pad couples the electrical signal to another portion ofthe touch pad in order to develop a detection signal. The touch padresponds to the presence of capacitance of a user in order toselectively attenuate the detection signal. A decoding circuit respondsto the detection signal in order to determine the presence of thecapacitance of a user.

According to one aspect of the invention, a source signal generator isprovided that generates a high frequency electrical signal having aprimary frequency that is greater than 150 kHz and preferably in therange of between 150 kHz and 500 kHz. Such high frequency electricalsignal may be a square wave, a triangular wave, a sawtooth wave, asinusoidal wave or some other waveform. This aspect of the invention isbased upon the discovery that touch controls operated at such primaryfrequencies have improved water immunity performance. According toanother aspect of the invention, the decoding circuit may include a peakdetector that is coupled directly with the detection signal, in order toproduce an output, and a switch circuit that is responsive to the outputof the peak detector in order to determine an amplitude of the outputindicative of attenuation of the source electrical signal. The peakdetector is preferably a low gain circuit in order to avoid distortingthe detection signal by exceeding the gain/bandwidth product of thecircuit and in order to avoid fast signal slew rates. The switch circuitis preferably coupled to the output of the peak detector by an amplifiercircuit. In this manner, amplification is performed on the lowerfrequency signal of the peak detector output rather than on the higherfrequency of the detection signal. The gain/bandwidth product of thesystem is not exceeded at any point in order to provide a more accuratedetection of the effect of a user contacting a touch pad and lowslew-rate components may be used to embody the invention.

According to another aspect of the invention, a touch control isprovided for a glass ceramic substrate having a user contact surface andan opposite modulated surface. A keypad is defined by a plurality oftouch pads, each of the touch pads having a pair of electricallyconductive elements affixed to the modulated surface. A signal generatoris provided that is adapted to generate an electrical signal and toapply the signal to one of the electrically conductive elements of atleast one of the touch pads. The electrical signal is passively coupledto the other one of the electrically conductive elements in order todevelop a detection signal. The touch pads respond to the presence ofcapacitance of a user in order to selectively attenuate the detectionsignal. A decoding circuit is provided that responds to the detectioncircuit in order to determine the presence of capacitance of a user.

According to yet another aspect of the invention, a display isjuxtaposed with the substrate modulated surface in order to providevisual indications to a user. An optical correction material is providedbetween the display and the substrate. The optical correction materialcorrects optical distortion of the visual indications of the displaycaused by the modulated surface. In a preferred embodiment, the opticalcorrection material is a transparent adhesive that adheres a flexiblecarrier carrying the display device and/or the touch pad flexibleconductor to the glass substrate.

The present invention overcomes the difficulties of the prior art byproviding a touch control that has greatly improved performance in thepresence of liquids, such as water, on the touch pads positioned on theuser interface surface of the substrate. Because the system's immunityto water is significantly improved, there is no necessity for aspecialized guard ring or for latching of the cooking appliance in anoff state in the presence of water. Accordingly, the user is notbothered by having to reset the power level of the burner when a liquidspill occurs. The present invention allows, for the first time, apractical application of a touch control to a glass ceramic-substratehaving a modulated rear surface. A touch control circuit is providedaccording to the invention which is capable of accommodating theelectrical characteristics of such substrate. In addition, a uniquemeans is provided to correct distortions of the image displayed by adisplay device and viewed through the dimpled, modulated surface of thesubstrate.

These and other objects, advantages and features of this invention willbecome apparent upon review of the following specification inconjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a system incorporating a touch controlaccording to the invention;

FIG. 2 is a sectional view taken along the lines II--II in FIG. 1;

FIG. 3 is an exploded perspective view from the top of the touch controlin FIG. 1;

FIG. 4 is a block diagram of a touch control according to the invention;

FIG. 5 is an electrical schematic diagram of a touch control accordingto the invention;

FIG. 6 is an illustration of an optical indicator without an opticalcorrection material; and

FIG. 7 is an illustration of an optical indicator with an opticalcorrection material according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now specifically to the drawings, and the illustratedembodiment depicted therein, a touch control 10 includes a generallyplanar substrate 12 and a plurality of touch pads, generally indicatedat 14 applied to substrate 12 (FIG. 1). Each touch pad 14 includes afirst portion composed of an electrically conducting element 16a and asecond portion composed of an electrically conducting element 16baffixed to a surface 18 of substrate 12, which faces away from the user(FIGS. 2-4). Each touch pad 14, in the illustrative embodiment, alsoincludes a user contact pad 20 overlying the conductive elements 16a and16b. User contact pads 20 are transparent conductive metallic oxidefilms applied by conventional sputtering or pyrolytic techniques. Touchcontrol 10 may additionally include indicators 22 in order to providevisual indication to the user of the condition of the appliance beingcontrolled (not shown). In the illustrated embodiment, substrate 12 is aglass ceramic member having a thickness in the range of three (3) tofive (5) millimeters in order to provide adequate strength forhorizontal applications in which mechanical stress may be applied to thesubstrate. One such application is a smooth-top cooking surface for a4-burner cooking appliance. In order to further enhance the strength ofsubstrate 12, surface 18 is modulated or dimpled (FIG. 2). Substrate 12is marketed under the mark "Ceran" by Schott Glass Company located inYonkers, N.Y.

In order to apply the conductive elements 16a, 16b of each touch pad tosurface 18 of substrate 12, the conductive elements 16a, 16b are mountedto a flexible carrier 24. Carrier 24 is adhered to surface 18 by anadhesive layer 26. Additionally, indicators 22 are mounted to flexiblecarrier 24 in order to locate the indicators in a position where theymay be viewed through substrate 12. In order to correct opticaldistortion created by the presence of the modulations, or dimples, onsurface 18, an optical correction material 23 is positioned betweenindicator 22 and modulated surface 18. Optical correction material 23has an index of refraction that is compatible with that of substrate 12and fills in the voids between the dimples of surface 18, as well as thespace between surface 18 and indicator 22. In this manner, light emittedby indicator 22 passes through substrate 12 without substantialdistortion.

Operation of optical correction material 23 may be understood bycomparing an indicator 22' in FIG. 6 with an indicator 22" in FIG. 7.Indicator 22' illustrates the optical effect of modulated surface 18.The different incidence angles of light rays caused by the dimplescreates a "fish-eye" effect whereby an initially homogeneous indicationtakes on the appearance of numerous circles and the indication hasserrated edges. In contrast, indicator 22" illustrates the correctiveeffect of optical correction material 23 in eliminating distortions tothe homogeneous appearance of the indicator, including retaining thecrisp edges of the initial indication.

Optical correction material, in the illustrated embodiment, is atransparent acrylic material. While optical correction material 23 isclear, it may be also dyed in order to modify the color of indicators22. A clear acrylic material in transfer adhesive form is commerciallyavailable from the 3M Company, Minneapolis, Minn., and marketed underType 300MP. In a most preferred embodiment, a clear acrylic adhesive,such as 3M Type 300MP, is applied to the entire interface betweensurface 18 and flexible carrier 24 at a thickness of 0.013 inches inorder to affix the flexible carrier to the substrate and to provideoptical correction material for indicators 22.

Touch control 10 includes an electronic control 30 having a highfrequency line driver 32 as a source for producing a high frequencypulsed signal at 34, which is applied to portion 16a of touch pad 14(FIGS. 4 and 5). This signal is capacitively coupled to portion 16b oftouch pad 14 in order to produce a detection signal at 36. When there isno user contacting the user contact pad 20 associated with touch pad 14,the very high frequency signal at 34 is coupled to detection signal 36without attenuation by the capacitance of the user's body. This isillustrated as the initial portion (left side) of the waveformillustrated at 36. When, however, a user engages the user contact pad 20associated with touch pad 14, the detection signal becomes attenuated toa lower amplitude as illustrated in the second portion (right side) ofthe waveform illustrated at 36 in FIG. 4. In the illustrated embodiment,portion 16a and 16b provide a 10-30 picofarad (pf) coupling between thehigh frequency signal at 34 and the detection signal at 36. Accordingly,a peak voltage, for example, of between five (5) and twelve (12) voltsproduced by the high frequency line driver may develop a detectionsignal at 36 on the order of magnitude of 70 mv.

The detection signal on line 36 is decoded by a peak detector 38, whichproduces an output 40, and an amplitude-responsive switch 42, whichresponds to the amplitude of output 40 in order to actuate appropriateindicators, power circuits and the like, as illustrated at 44. Highfrequency line driver 32 has a primary frequency that is at least equalto 150 kHz. It has been discovered that, for primary frequencies of 150kHz and above, touch control 10 has increased immunity to cross-couplingbetween adjacent touch pad 14 due to liquids, such as water, onsubstrate 12. While it is believed that most frequencies above 150 kHzwould provide improved liquid immunity, considerations of componentconfigurations of control system 30 would suggest a practical upperlimit of approximately 500 kHz on the primary frequency for line driver32. In the illustrated embodiment, line driver 32 has a primaryfrequency of 250 kHz. In the illustrated embodiment, the output signalof high frequency line driver 32 is a square wave varying between zerovolts and an upper limit, such as five volts. When coupled throughportions 16a and 16b of touch pad 14, the detection signal at 36 is asquare wave which oscillates equally at both polarities with respect tosignal ground. Alternatively, high frequency line driver 32 couldproduce other waveforms, such as a triangle, sawtooth or sinusoidalwaveform.

Another advantage of utilizing a high frequency line driver as a sourcefor control system 30 is that the waveform of the detection signal at 36retains its original waveform notwithstanding the relatively smallcoupling capacitance between conductive elements 16a and 16b. Thus, thetendency of prior art systems to distort the waveform of the detectionsignal by coupling the higher frequency primary component to anoticeably greater extent than the lower frequency components of thesquare wave is reduced because all frequency components are at orgreater than the primary frequency, which is at a high frequency. Thisprovides a more efficient coupling which is desirable to offset theeffects of the greater thickness of substrate 12. Furthermore, theoutput of peak detector 38, at 40, exhibits a relatively flat amplitudefor both the attenuated and non-attenuated conditions of detectionsignal at 36. This improves the reliability of the system by increasingthe distinction between touched and non-touched conditions of touch pad14. Furthermore, in contrast to prior systems in which the detectionsignal at 36 is amplified prior to decoding, peak detector 38 is coupleddirectly with the detection signal at 36. Because, in the illustratedembodiment, peak detector 38 has a low gain, the gain/bandwidth productof the system accommodates the very high frequency of line driver 32without distortion of the signal. The gain/bandwidth product, as is wellunderstood to those skilled in the art, is a constant for each systemand dictates that the frequency band multiplied by the gain of eachamplifier cannot exceed a predefined constant without distorting thesignal. The output 40 of peak detector 38, in contrast, is a relativelylow frequency signal having a significant DC component. Accordingly,desirable amplification can be applied to output 40 byamplitude-responsive switch 42 without compromising the gain/bandwidthproduct of the system. In addition, the output 40 of peak detector 38has a limited amplitude range. Therefore, components utilized in peakdetector 38 are not required to have a high slew-rate capability, whichreduces the expense of such components.

Although control system 30 has been described as it applies to anindividual touch pad 14, the same principles are applicable to a keypad15 composed of multiple touch pads 14 wherein known multiplexingtechniques are utilized to apply high frequency line driver 32 and peakdetector 38 sequentially to touch pads 14a, 14b . . . 14n in a strobedfashion. Such a system is illustrated in FIG. 5 in which a 250 kHzpulsed signal generator 46 has an output 47 that is applied to ademultiplexing circuit 48. Under the control of an output line 49 of amicrocomputer 50, demultiplexer 48 sequentially applies the output ofsignal generator 46 to driver lines 52a, 52b and 52c. Because of thesequential nature of the application of the drive signal to the drivelines, the drive signal appears as a burst of high frequency pulses oneach of the drive lines 52a-52c. The pulse bursts, in turn, producedetection signals on sense lines 54a-54d, which are connected todifferent groups of touch pads 14a-14n than the pads connected to driverlines 52a-52c. The sense lines 54a-54d are provided as inputs to amultiplex circuit 56, which is under the control of microcomputer 50,via line 55, in order to synchronize multiplex circuit 56 with theoperation of the demultiplex circuit 48. Because multiplex circuit 56 isa switching device, which sequentially applies each sense line 54a-54dto detection signal line 57 connected with peak detector 38, the peakdetector is directly coupled sequentially with each of the sense lines54a-54d.

Peak detector 38, in the illustrated embodiment, is composed of anoperational amplifier 58 whose output 59 is connected by a diode 60 withits inverting input 61. Diode 60 is also connected, through a resistor63, with output 40. Detection signal line 57 is connected with thenon-inverting input of amplifier 58. Detection signal line 57 isadditionally connected to signal ground through a pull-down resistor 62.This configuration is a low gain peak detector because the directconnection feedback provides amplifier 58 with a unity gain.Alternatively, diode 60 could be replaced with a short circuit and adiode connected between output 59 and resistor 63. Output 40 is filteredby a filter 64 in order to complete the peak detect function of peakdetector 38. Filter 64 is composed of a parallel combination of resistor66 and capacitor 68 connected between output 40 and signal ground.

In the illustrated embodiment, pull-down resistor 62 is a 10 kohmresistor. This provides very low input impedance to peak detector 38which, advantageously, imparts exceptional static electricity resistanceto touch control 10. Static charges applied to substrate 12 are rapidlydissipated through resistor 62. This low input impedance is possiblebecause of the exceptional signal strength of the detection signal as aresult of the very high frequency primary component of the drive signal,as well as the equivalent resistance/capacitance value (RC) of thisportion of the circuit.

Output 40 is provided to the non-inverting input of an amplifier 70. Abiasing network composed of resistors 72a and 72b connected in aconventional fashion between an inverting input of amplifier 70 and itsoutput 88 establishes the gain of amplifier 70. As previously described,because the signal on output 40 of peak detector 38 has a relatively lowfrequency content, the gain of amplifier 70 may be set at a relativelyhigh level without exceeding the gain/bandwidth product of the systemand without creating high slew rates. In the illustrated embodiment, thevoltage gain of amplifier 70 is between 80 and 100.

In order to detect the capacitance of a user contacting one of the touchpads 14a-14n, output 88 of amplifier 70 is applied to anamplitude-responsive switching circuit, which in the illustratedembodiment is a successive approximation register 74 controlled withmicrocomputer 50. Successive approximation register (SAR) 74 provides ahighly accurate means to allow microcomputer 50 to determine relativeamplitude of output 88 of amplifier 70. SAR 74 includes a resistancenetwork 76, which is composed of a ladder of resistances which vary fromeach other in multiples of two. Therefore, such network is referred toas an R2R network. The R2R network 76 is utilized by microcomputer 50 inorder to produce an analog signal at 78 as a function of the combinationof output lines 75 actuated by the microcomputer. The analog signal at78 is scaled by an amplifier 80 whose scaling factor is established bybias resistors 82a and 82b connected in conventional fashion withrespect to its output 84 and inverting input. Output 84 is connectedwith the inverting input of a comparator 86 whose non-inverting input isconnected with output 88. The output of 90 of comparator 86 is providedas an input to microcomputer 50.

SAR 74 operates as follows. In order to determine the relative analogvoltage at output 88, microcomputer 50 actuates a combination of outputlines 75 representative of a known relative analog voltage at output 84of scaling amplifier 80. Comparator 86 will compare this analog voltageat 84 with the analog voltage at output 88 of amplifier 70. Output 90 ofcomparator 86 will assume one of two alternate states depending uponwhether the approximate voltage produced at output 84 is greater than,or less than, the output voltage 88 of amplifier 70. Microcomputer 50interprets the state of output 90 in order to adjust the states ofoutput line 75 and vary the analog voltage at 84 until it issubstantially equal to the analog voltage at 88. Microcomputer 50 thenmakes a determination whether such analog voltage represents a touchedor non-touched condition for the associated touch pads 14a-14n. Suchdetermination is made in software resident in microcomputer 50 in themanner disclosed in U.S. Pat. No. 5,189,417 issued to David Caldwell andNicholas Medendorp for a DETECTION CIRCUIT FOR MATRIX TOUCH PAD, thedisclosure of which is hereby incorporated herein by reference, exceptthat relative amplitude is used in circuit 30 to determine a touch/notouch condition rather than relative pulse-width used as in the '417patent. Microcomputer 50 may then actuate the appropriate elements ofindicator 22, power relays or the like at output 44 depending upon theresponses programmed within the microcomputer for various combinationsof input selections by the user contacting touch pads 14a-14n.

Successive approximation registers (SARs) are well known in the art. Theadvantage of such an SAR is that it provides a higher resolutiondetection of the relative analog voltage at output 88 of amplifier 70than would be possible by coupling output 88 directly to an analog inputport of microcomputer 50. However, in certain applications, it may bepossible to read the analog level of output 88 of amplifier 70 at ananalog input port to microcomputer 50. In the illustrated embodiment,SAR 74 is capable of reading the relative analog voltage level at output88 to an accuracy of nine bits. In contrast, present commerciallyavailable microprocessors that are capable of eight-bit accuracy orgreater, in a determination of analog input voltages, are relativelyexpensive.

The unique principles of the present invention allow the application oftouch control technology directly to the unique environment of a largehorizontal substrate of the type found in smooth cook tops and the like.The hurdle of the use of a substrate that not only has an exceptionallylarge thickness but also a modulated rear surface is overcome. Circuitmeans are provided that provide sufficient signal differentiation toaccommodate the dielectric of such substrate. Advantageously, theinvention additionally provides exceptional immunity to the splashing ofliquids, such as water, on the touch control touch pads. The circuitmeans also advantageously imparts an exceptionally effective staticelectricity (ESD) immunity to the system. In addition, the inventionprovides a means for incorporating a display device which produces clearand crisp images notwithstanding the detrimental effect of the modulatedrear surface of the substrate. These features allow the touch control tobe applied directly to the substrate defining smooth-top cook top. Thus,the requirement for a physical barrier between the separate substratesdefining a cook top and a touch control in prior systems is completelyeliminated. This is accomplished in a manner which does not requireguard rings or the detrimental operation of shutting down the rangewhenever liquid is splashed on the touch control. Furthermore, safety isenhanced because the present system does not require the use of aseparate substrate which may have a reduced thickness from the cook toppan supporting substrate. Thus, the potential of breakage of suchthinner substrate is avoided.

Although the present invention has been described as applied tomodulated glass ceramic cook tops, its principles may be used in otherapplications. For example, the invention may be applied to substratesother than modulated glass ceramic cook tops and may be applied tovertical applications, especially where it is desired to enjoy immunityfrom the splashing of water and the like. Other changes andmodifications in the specifically described embodiment can be carriedout without departing from the principles of the present invention,which are intended to be limited only by the scope of the appendedclaims as interpreted according to the principles of patent law,including the Doctrine of Equivalents.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A moisture immune touchcontrol circuit for use with a substrate comprising:a touch responsivecircuit including at least one touch pad which produces a detectionsignal in the presence of capacitance of a user at said touch pad,wherein said detection signal is substantially immune to the presence ofmoisture; and a decoding circuit that responds to said detection signalin order to determine the presence of said capacitance of a user, saiddecoding circuit including a successive approximation register circuitin order to determine an amplitude of said detection signal.
 2. Thetouch control circuit in claim 1 wherein said successive approximationregister circuit includes a resistance network driven by a microcomputerto produce an approximation signal and a comparator to compare saiddetection signal with said approximation signal.
 3. The touch controlcircuit in claim 2 wherein said successive approximation registercircuit includes a scaling circuit to scale said approximation signal.4. The touch control circuit in claim 1 including a carrier supportingand electrically interconnecting components defining said touchresponsive circuit and said decoding circuit.
 5. The touch controlcircuit in claim 1 wherein said decoding circuit has an input impedanceof less than approximately 10 kohms.
 6. The touch control circuit inclaim 4 including an indicator mounted to said carrier for displayingoutputs of said decoding circuit.
 7. The touch control circuit in claim6 wherein said carrier is a flexible carrier.
 8. The touch controlcircuit in claim 4 wherein said carrier is a flexible carrier.
 9. Thetouch responsive circuit in claim 1 wherein said at least one touch padincludes a pair of electrically conductive elements.
 10. The touchresponsive circuit in claim 9 including a signal generator for applyinga signal to one of said elements, the capacitance of a user couplingsaid signal to the other of said elements as said detection signal. 11.The touch responsive circuit in claim 7 including an adhesive foraffixing said flexible carrier to a substrate.
 12. A moisture immunetouch control circuit which is static electricity resistant for use witha substrate comprising:a touch responsive circuit including at least onetouch pad which produces a detection signal in the presence ofcapacitance of a user at said touch pad, wherein said detection signalis substantially immune to the presence of moisture; and a decodingcircuit the responds to said detection signal in order to determine thepresence of said capacitance of a user, said decoding circuit comprisinga low gain detector circuit, an amplifier and an impedance element, saiddetector circuit having an input coupled with said touch responsivecircuit to receive said detection signal and an output coupled with saidamplifier, said impedance element connected between said input and aground providing an input impedance for said decoding circuit of lessthan approximately 10 kohms.
 13. The touch control circuit in claim 12including a carrier supporting and electrically interconnectingcomponents defining said touch responsive circuit and said decodingcircuit.
 14. The touch control circuit in claim 13 including anindicator mounted to said carrier for displaying outputs of saiddecoding circuit.
 15. The touch control circuit in claim 14 wherein saidcarrier is a flexible carrier.
 16. The touch control circuit in claim 13wherein said carrier is a flexible carrier.
 17. The touch controlcircuit in claim 16 including an adhesive for affixing said flexiblecarrier to a substrate.
 18. The touch control circuit in claim 12wherein said detector circuit is a peak detector circuit.
 19. The touchcontrol circuit in claim 18 wherein said peak detector circuit has asubstantially unity gain.
 20. The touch control circuit in claim 12wherein said detector circuit has a substantially unity gain.
 21. Thetouch control circuit in claim 12 wherein said impedance element has animpedance value of less than approximately 10 kohms.
 22. A touch controlcircuit for use with a substrate comprising:a touch responsive circuitincluding at least one touch pad which produces a detection signal inthe presence of capacitance of a user at said touch pad; and amicrocomputer having an output which operates a resistance network inorder to produce an analog signal, a comparator which compares saidanalog signal with said detection signal and produces a digital signalwhich is supplied as an input to said microcomputer, said digital signalhaving a state which is a function of the relative amplitudes of saidanalog signal and said detection signal, wherein said microcomputer isprogrammed to adjust said output while monitoring said input in a mannerwhich determines whether said detection signal represents the presenceof capacitance of a user at said touch pad.
 23. The touch controlcircuit in claim 22 wherein said decoding circuit has an input impedanceof less than approximately 10 kohms.
 24. The touch control circuit inclaim 22 including a carrier supporting and electrically interconnectingcomponents defining said touch control circuit.
 25. The touch controlcircuit in claim 24 including an indicator mounted to said carrier fordisplaying outputs of said decoding circuit.
 26. The touch controlcircuit in claim 25 wherein said carrier is a flexible carrier.
 27. Thetouch control circuit in claim 24 wherein said carrier is a flexiblecarrier.
 28. The touch control circuit in claim 27 including an adhesivefor affixing said flexible carrier to a substrate.
 29. The touch controlcircuit in claim 22 wherein said at least one touch pad includes a pairof electrically conductive elements.
 30. The touch control circuit inclaim 29 including a signal generator for applying a signal to one ofsaid elements, the capacitance of a user coupling said signal to theother of said elements as said detection signal.